An AIDS Collaborative Team (ACT) from UCLA, the Chinese Academy of Preventive Medicine and Shanghai School of Public Health proposes to implement the Popular Opinion Leader (POL) model for HIV prevention among migrant workers from 20 villages in Anhui Province, China. China, representing 1/4th of the world's population, has a rapidly emerging HIV epidemic with about 1.2 million already infected, more than the total of all the Asian nations combined. Similar to Africa and India, the country's 200-250 million labor migrants are a key to the epidemic's future, however, HIV infection is redominantly occurring in rural settings (75 percent of population) and migrants transmit the virus heterosexually when moving to the cities annually. While migrants travel for jobs, all migrants return to villages twice a year (allowing biannual follow-up assessments with greater than 90 percent retention) and for about 4 months a year to be exposed to the intervention. A village-focused intervention is proposed with supplementary HIV prevention activities in the costal cities. During Phase 1, two activities are proposed: 1) an ethnographic study to inform the intervention design; and 2) feasibility studies of village selection, HIV/STD rates, and development of assessment and quality assurance procedures. Building on the ethnography, in Phase 2, a pilot study of the proposed POL intervention will be conducted in 1 village with a contrast village to test implementation of all procedures. In Phase 3, the main trial, randomization will occur first at the level of region, the Northern and Southern Regions of Fuyang Prefecture within Anhui Province. Within one region, 10 villages will be randomly selected and 10 villages will be matched in the other region (on SES, size, percent of migrants, and literacy) resulting in 120 migrant POL; 630 migrants; 1,500 villagers per region. Once matched, villages within region will be randomly assigned to either: 1) the POL intervention that includes HIV prevention social marketing campaigns, POL training to diffuse prevention messages, and ongoing access in villages and cities to HIV/STD testing, condoms, and treatment for STD; or 2) a non- intervention control condition. Over 24 months, HIV-related primary (STD/HIV rates, sexual risk) and secondary (social norms, rate of adoption) outcomes will be assessed among migrants and the non-migrant villagers in the intervention condition compared to those in the control condition at baseline, 6, 12, 18 and 24 months. In Phase 4, analysis and dissemination of the results will be completed. The ACT's ability to successfully implement the project is based on: previous successful HIV prevention trials including interventions in China, and participation in HIV-related cooperative agreements; support of the project from experienced Chinese collaborators, officials and organizations; access to sites in China; collaboration with experienced Chinese investigators several of whom have trained at UCLA; and collaboration of the Qualitative Core of the UCLA-NPI.